Network Data Management Protocol (NDMP) is a mechanism and a protocol to move data between primary storage and secondary storage. It is used by network-attached storage (“NAS”) systems to back up and/or restore data. As the capacity of data stored on NAS systems increases due to industry demand and corresponding technological advances, backing up these storage systems becomes more challenging. For example, although the amount of data to be backed up tends to increase as the capacity of a NAS system increases, in general, the backup window allotted for performing backups does not change. This can be because backups are run during off-peak hours of NAS usage so as not to compete for system resources with non-backup users during peak hours.
One means for providing more efficient backup solutions is through incremental backup. In general, rather than backing up every object in a NAS storage system, incremental backup backs up only those objects that have changed since the previous backup. During a typical incremental backup of a dataset, a backup server traverses through the dataset by doing a treewalk and compares the change time of each object, e.g., a file or directory, against a time value, e.g., the last backup time. If an object's change time is greater than the time of the last backup, then the object is selected for backup. This treewalk process checks every object in the dataset no matter how many objects changed since the last backup. However, by checking every object of the dataset, the backup system, in most use cases, will end up checking objects that do not need to be backed up. One example consequence of such inefficiency is causing the backup server to fail to match the tape speed of the backup storage device. Thus, for each write to the backup storage tape, the tape drive can be forced to rewind the tape, reposition the tape, speed up the tape, etc. This is called a shoe-shining effect which prevents the tape drive from operating at maximum efficiency. Thus, there exists to continue to optimize incremental backup processes for greater efficiency that can reduce or even prevent the shoe-shining effect.